package com.atcumt.Huawei;

import java.util.*;
import java.util.stream.Collectors;

public class HJ001 {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        List<String> list = Arrays.asList(s.split(""));
        Set<String> set = new HashSet<>(list);
        System.out.println(set.size());
    }
}
